1. FIELD OF THE INVENTION
This invention relates to a lightweight solar cell, particularly a cell having a substrate of low density.
2. THE PRIOR ART
The current state of the art in solar cell design is to deposit a photoconductive material onto a substrate, e.g. of glass or a low expansion glass ceramic. These substrate materials have densities of approximately 2.2 gms/cc (2200 mg/cc) or higher. Accordingly, the weight of an array or battery of such prior art solar cells is a determining factor in the size of the battery system to be launched into space due to payload weight constraints. However, if a lighter weight cell substrate could be fabricated, the resulting savings in
size for weight would translate into an increased allowable size for satellite photovoltaic energy systems, which implies higher reliability and accessibility of the satellite throughout its life cycle.
There has now been discovered a method of manufacture of lightweight solar cells having a substrate density considerably below, eg. 2200 mg/cc of the above prior art glass substrates. In fact, the present invention provides cell substrates of greatly reduced densities, e.g. in the range of 30-1,000 mg/cc, to provide a significant decrease in solar cell array weight.
The present invention employs a solar cell substrate of low density or LD. By low density or LD substrate, as used herein, is meant one with a density of from 10-1,000 mg/cc.